We are a medical and nursing family — I'm a retired nurse, and my husband, brother and sister-in-law are doctors — and we'd long since had her undergo exhaustive tests to check for serious underlying conditions. The tests had revealed nothing other than a slow heart rate and an occasional drop in blood pressure. At 93, Mom was resolutely independent, although in recent years she had preferred to stay at home where, day or night, she knew the lay of the land and felt safe. While caring for someone else's elderly mother or grandmother during my nursing days, I had always accepted the patient's mental condition at face value.